An apparatus (7) for down-converting a sampled signal comprises a processing system (206) configured to apply a mixing-and-combining operation repeatedly to successive sub-sequences of N input samples, X, representative of a signal and having an initial sampling rate, M, to generate a sequence of output samples, Y, having an output rate, T, lower than the initial sampling rate M. The sub-sequences of the N input samples, X, are spaced at intervals that correspond to the output rate M. The mixing-and-combining operation generates a respective output sample Y from each sub-sequence, where Y depends on a set of products of the input samples X of the sub-sequence with respective values derived from a periodic mixing signal having a mixing frequency.

An apparatus (7) for down-converting a sampled signal comprises a processing system (206) configured to apply a mixing-and-combining operation repeatedly to successive sub-sequences of N input samples, X, representative of a signal and having an initial sampling rate, M, to generate a sequence of output samples, Y, having an output rate, T, lower than the initial sampling rate M. The sub-sequences of the N input samples, X, are spaced at intervals that correspond to the output rate M. The mixing-and-combining operation generates a respective output sample Y from each sub-sequence, where Y depends on a set of products of the input samples X of the sub-sequence with respective values derived from a periodic mixing signal having a mixing frequency.

A method for use in acoustic imaging, comprising: transmitting, from a transmitter, a first sound wave pulse at a first frequency determined by a maximum sampling rate of a receiver; transmitting at least one second sound wave pulse at a frequency substantially equal to the first frequency, the first and at least one second sound wave pulses being transmitted substantially within a fraction of a sample interval of the receiver; receiving and sampling, at the receiver, a reflection of at least two of the first and at least one second pulses to generate a set of receiver samples; and expanding the set of receiver samples, based on the first frequency and a total number of the first and at least one second pulses transmitted, to generate an expanded sample set with a larger number of samples than the set of receiver samples.

A method for use in acoustic imaging, comprising: transmitting, from a transmitter, a first sound wave pulse at a first frequency determined by a maximum sampling rate of a receiver; transmitting at least one second sound wave pulse at a frequency substantially equal to the first frequency, the first and at least one second sound wave pulses being transmitted substantially within a fraction of a sample interval of the receiver; receiving and sampling, at the receiver, a reflection of at least two of the first and at least one second pulses to generate a set of receiver samples; and expanding the set of receiver samples, based on the first frequency and a total number of the first and at least one second pulses transmitted, to generate an expanded sample set with a larger number of samples than the set of receiver samples.

This invention relates to a method of improving performance of a SODAR system adapted to locate discontinuities in the atmosphere by transmitting pulse compression signals such as a plurality of acoustic chirps, the method comprising: transmitting one or more acoustic chirps; receiving one or more acoustic echoes of the transmitted chirps; processing the acoustic echoes to provide an indication of the discontinuities in the atmosphere, thereby providing a wind shear profile; processing the wind shear profile to correct systematic Doppler errors associated with the acoustic echoes by: subtracting a first measured wind speed from the wind shear profile; and adding a second measured wind speed to the wind shear profile.

This invention relates to a method of improving performance of a SODAR system adapted to locate discontinuities in the atmosphere by transmitting pulse compression signals such as a plurality of acoustic chirps, the method comprising: transmitting one or more acoustic chirps; receiving one or more acoustic echoes of the transmitted chirps; processing the acoustic echoes to provide an indication of the discontinuities in the atmosphere, thereby providing a wind shear profile; processing the wind shear profile to correct systematic Doppler errors associated with the acoustic echoes by: subtracting a first measured wind speed from the wind shear profile; and adding a second measured wind speed to the wind shear profile.

An underwater detection apparatus is provided which includes a transmission transducer, a reception transducer, and a motor. The transmission transducer transmits a transmission wave within a given fan-shaped transmission space, the fan-shaped transmission space having a first transmission width in a given first plane and a second transmission width in a second plane perpendicular to the first plane. The reception transducer receives, as a reception wave, a reflection wave of the transmission wave within a given fan-shaped reception space, the fan-shaped reception space having a first reception width in the first plane and a second reception width in the second plane, the second reception width being wider than the second transmission width, and in the second plane, the fan-shaped transmission space being within the fan-shaped reception space. The motor rotates the fan-shaped transmission space and the fan-shaped reception space.

An integrated circuit may include a ranging receiver that includes an analog-to-digital converter (ADC) having a time-variant sampling or data rate. Notably, the sampling rate may be increased when a return signal is detected by the ranging receiver. For example, the return signal may be detected using a matched filter (such as a correlation of the return signal and a target signal) and a comparator having a time-variant threshold. The time-variant threshold may be decreased as a function of time after a transmit signal is output in order to track the channel response, such as a decrease in the return signal amplitude for objects at larger ranges. Alternatively or additionally, the sampling rate may be increased based at least in part on a predefined function (such as a closed-form expression or a stepwise function, e.g., a stairstep function) after the transmit signal is output.

An object detection apparatus detects an object in a vicinity of a moving body in a state of being mounted to the moving body. The object detection apparatus measures a reverberation frequency that is a frequency of a reverberation signal that is generated in a transceiver that externally transmits a transmission wave that is an ultrasonic wave and receives a reception wave that includes a reflected wave of the transmission wave from the object. object detection apparatus detects the object based on the reception wave. The object detection apparatus sets at least one of a transmission characteristic and a reception characteristic in the transceiver. The object detection apparatus sets at least one of transmission characteristics of the transmission wave and/or sets circuit characteristics in the transceiver. The object detection apparatus reduces at least one of the transmission characteristic and the reception characteristic during measurement of the reverberation frequency.

A dynamic power reduction method and apparatus for use in an ultrasound system are described. In one embodiment, the ultrasound system comprises: a transducer assembly and imaging subsystem having a transmit data path having a transmitter to transmit acoustic signals and a receive data path having including signal acquisition circuitry with a receiver to receive acoustic signals representing echoes; a plurality of real-time signals indicative of status of imaging operations being performed by the transmit and receive paths; a clock generator to generate one or more clocks for use by the transmit and receive data paths; clock gating circuitry coupled to the clock generator and the transmit and receive paths and having circuits to gate clocks to at least one of the transmit and receive paths; and a clock gating controller coupled to the clock gating circuitry to control the circuits to gate or pass clock signals to at least one of the transmit and receive paths automatically in response to receipt of one or more signals from the plurality of real-time signals.